Piston rod clamping system

ABSTRACT

A system, in certain embodiments, includes a piston clamping system including a piston rod comprising a piston rod shoulder and a piston rod nut coupled to the piston rod, wherein the piston rod nut and the piston rod shoulder are configured to axially capture first and second body portions of a piston therebetween.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefit of U.S. Non-Provisionalpatent application Ser. No. 13/674,925, entitled “LIGHT COMPOSITEPISTON”, filed Nov. 12, 2012.

BACKGROUND

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

A piston may include a disk or cylinder that moves within aclose-fitting cylinder of a mechanical assembly. The piston within thecylinder operates to transfer force from a working fluid to a shaft, orvice versa. The piston may include a crosshead designed to reduce oreliminate lateral, or radial, pressure on the piston during operation.For example, mechanical assemblies such as engines, pumps, andcompressors include cylinders with reciprocating pistons. In engines,the piston moves in response to a fluid pressure resulting fromcombustion of a fuel-oxidant mixture. More specifically, the force fromthe fluid pressure is transferred to the piston, which further transfersthe force to a shaft. Conversely, pumps and compressors include pistonsfor compressing or ejecting a fluid within a respective cylinder. Thepump or compressor includes a shaft which transfers force from aconnecting rod, a crosshead, a piston rod, and the piston to a workingfluid, such that the working fluid is compressed within or displacedfrom the cylinder. Unfortunately, the speed of the piston and crosshead,and therefore the flow capacity of the mechanical assembly, may belimited by the construction of the piston.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features, aspects, and advantages of the present invention willbecome better understood when the following detailed description is readwith reference to the accompanying figures in which like charactersrepresent like parts throughout the figures, wherein:

FIG. 1 is a perspective view of a reciprocating compressor including alight composite crosshead and/or a light composite piston in accordanceembodiments of the present disclosure;

FIG. 2 is an axial cross-sectional view of the exemplary compressor ofFIG. 1, including a light composite crosshead and/or a light compositepiston, in accordance with embodiments of the present disclosure;

FIG. 3 is a cross-sectional side view of a light composite piston, inaccordance with embodiments of the present disclosure;

FIG. 4 is a partial cross-sectional view taken within line 4-4 of FIG.3, illustrating an embodiment of the composite material having areinforcing material distributed within a matrix material;

FIG. 5 is an exploded view of a light composite piston assembly, inaccordance with embodiments of the present disclosure;

FIG. 6 is a cross-sectional side view of the light composite pistonassembly of FIG. 5, in accordance with embodiments of the presentdisclosure;

FIG. 7 is a schematic of an exemplary piston cylinder system including alight composite piston, in accordance with embodiments of the presentdisclosure;

FIG. 8 is a side view of a light composite crosshead, in accordance withembodiments of the present disclosure;

FIG. 9 is a cross-sectional side view of a crosshead pin, in accordancewith embodiments of the present disclosure;

FIG. 10 is a cross-sectional side view of a light composite crossheadpin, in accordance with embodiments of the present disclosure;

FIG. 11 is a perspective view a light composite crosshead, in accordancewith embodiments of the present disclosure;

FIG. 12 is a schematic of a compressor having a crosshead lubricationsystem, in accordance with embodiments of the present disclosure; and

FIG. 13 is a schematic of a piston rod and a piston assembly nut of apiston rod clamping system, in accordance with embodiments of thepresent disclosure.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

One or more specific embodiments of the present invention will bedescribed below. These described embodiments are only exemplary of thepresent invention. Additionally, in an effort to provide a concisedescription of these exemplary embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Moreover, the use of “top,” “bottom,” “above,” “below,” and variationsof these terms is made for convenience, but does not require anyparticular orientation of the components.

Certain embodiments of the present disclosure include a pistonconstructed of a lightweight composite material or other lightweightmaterial. For example, the lightweight composite material may be amaterial formed from a matrix material and a reinforcing material. Forexample, the reinforcing material may include particles, fibers, or thelike, distributed throughout the matrix material. In other embodiments,the lightweight composite material may include metal components,non-metal components, and/or ceramic composite components. The pistonmay be configured for use in a reciprocating compressor, engine, pump,or the like. In certain embodiments, the lightweight composite pistonmay have a single piece design or a multi-piece design. In embodimentsof the lightweight composite piston having a multi-piece design, thepiston may comprise two or more hollow piston halves or rings, eachhaving one or more internal stiffening ribs configured to increasestrength of the piston. Embodiments of the lightweight composite pistonfurther include a piston ring carrier configured to receive and supporta piston ring. As will be appreciated, a piston ring (e.g., pressurering) may serve to provide a gas-tight seal between the piston and thepiston cylinder as the piston moves within the piston cylinder (e.g.,during a compression stroke). Additionally, certain embodiments mayinclude a piston rod constructed of a composite material. As discussedin detail below, the lightweight composite piston, rod, and associatedcomponents may be constructed from a variety of lightweight materials.Advantageously, the lightweight material construction of the piston androd allows the piston to be operated at higher speeds and/or enableslarger sized pistons and larger fluid capacity/delivery for the sameweight as pistons and cylinders of conventional design. In the case ofhigher speed, the compressor, pump, engine, or other machine operatingthe piston may realize a larger fluid flow capacity without increasingthe size of the piston cylinder. It should be noted that the disclosedembodiments are described in the context of a compressor. However, othermachines may include the disclosed embodiments, such as a combustionengine, pump, or other reciprocating machine.

Certain embodiments of the present disclosure include a piston rodclamping system configured to assemble components of a piston assemblyhaving a multi-piece configuration. In certain embodiments, the pistonrod, on the piston side of a piston assembly may be designed to clampthe piston assembly together. For example, a piston rod nut and thepiston rod may each have threads that engage with one another to securethe piston rod nut to the piston rod on a first side (e.g., first axialside) of the piston assembly. The piston rod may also have a shoulder orflange disposed on a second side (e.g., second axial side) of the pistonassembly. As the piston rod nut is threaded onto the piston rod, thepiston rod nut and the collar, flange, or shoulder of the piston rod mayapproach one another on opposite sides of the piston assembly, therebyaxially compressing the components of the piston assembly together andassembling the piston assembly.

Additionally, certain embodiments of the present disclosure include acrosshead constructed of a lightweight composite material or otherlightweight material. For example, the lightweight composite materialmay be a material formed from a matrix material (e.g., a ceramicmaterial) and a reinforcing material (e.g., particles or fibersdistributed throughout the matrix material). In other embodiments, thelightweight composite material may include metal components andnon-metal components. The crosshead may be configured for use in areciprocating compressor, engine, pump, or the like. In certainembodiments, the light composite crosshead may also include a crossheadpin made of a light composite material. Embodiments of the lightcomposite crosshead pin may be configured to act as a bearing surfacebetween the crosshead and a connecting rod. Specifically, the lightcomposite crosshead pin may be configured to supply oil or otherlubricant to crosshead, pin, and crankshaft surfaces. As discussed indetail below, the lightweight composite crosshead may be constructedfrom a variety of lightweight materials. Advantageously, the lightweightmaterial construction of the crosshead allows the crosshead to beoperated at higher speeds. In this manner, the compressor, pump, engine,or other machine operating the crosshead may realize a larger flowcapacity without increasing the size of the piston cylinder.Additionally, the lightweight construction may provide additionalbenefits, as discussed below.

Furthermore, certain embodiments of the present disclosure include acrosshead lubrication system for a crosshead in a mechanical assembly,such as a compressor, engine, pump, or the like. For example, thecrosshead lubrication system may include a crosshead and a crosshead pin(e.g., an annular crosshead pin) configured to receive a flow of alubricant, such as oil, from a connecting rod and flow the lubricant toexterior or outer surfaces of the crosshead. For example, in oneembodiment, the lubricant may flow from the connecting rod towards thecrosshead and enter an annulus of the crosshead pin through entry ports.Thereafter, the lubricant may pass through exit ports of the crossheadpin and into lubricant ports of the crosshead. In this manner, thelubricant may reduce friction, abrasion, and/or wear between thecrosshead and the crosshead pin. Moreover, the lubricant further flowsthrough the lubricant ports of the crosshead, which extend from thecrosshead pin (e.g., at an interior of the crosshead) to an exterior ofthe crosshead. More specifically, the lubricant ports of the crossheadextend to recesses formed in exterior or outer surfaces of thecrosshead. As discussed in detail below, the outer surfaces of thecrosshead translate along crosshead guides of the mechanical assembly(e.g., compressor). Consequently, as the lubricant exits the lubricantports and flows within the recesses formed in the exterior surfaces ofthe crosshead, the lubricant may reduce friction, abrasion, and/or wearbetween the crosshead and crosshead shoes and/or the crosshead guides asthe crosshead moves within the mechanical assembly. In certainembodiments of the lightweight crosshead and crosshead pin, certaincomposite materials may be used to form the crosshead and the crossheadpin that may reduce the quantity of lubricant used due to aself-lubricating capacity or quality of such composite materials.

Turning now to the figures, FIG. 1 is a perspective view of an exemplarycompressor 10. In the illustrated embodiment, the compressor 10 includesa pair of compression cylinders 12 coupled to a frame 14. A variety ofinternal components may be disposed within the cylinders 12 and theframe 14 to enable compression of fluids introduced into the compressor10. For example, as discussed in greater detail below, the cylinders 12may include a crosshead formed from a composite material. In oneembodiment, the compressor 10 may be utilized to compress natural gas.However, in other embodiments, the compressor 10 may be configuredand/or utilized to compress other fluids.

A mechanical power source or driver 16, such as an engine or an electricmotor, is coupled to the compressor 10 to provide mechanical power tothe various internal components and enable compression of the fluidwithin the cylinders 12. To facilitate access to such internalcomponents, as may be desired for diagnostic or maintenance purposes,openings in the frame 14 may be provided and selectively accessed viaremovable covers 18. Further, the cylinders 12 also include valveassemblies 20 for controlling flow of the fluid through the cylinders12.

Although the exemplary compressor 10 shown is a two-throw reciprocatingcompressor, other compressors 10 may have alternative configurations.For instance, in other embodiments, the compressor 10 may include adifferent number of cylinder throws, such as a four-throw compressor, asix-throw compressor, a couple-free reciprocating compressor, a screwcompressor, or the like. Further, other variations in the compressor 10may include variations in the length of stroke, the operating speed, andthe size, to name a few.

FIG. 2 is a cross-sectional view of the compressor 10, which illustratesa number of exemplary internal components of the compressor of FIG. 1.In the illustrated embodiment, the frame 14 of the compressor 10includes a hollow central body or housing 22 that generally defines aninterior volume 24 in which various internal components may be received,such as a crankshaft 26. In one embodiment, the central body 22 may havea generally curved or cylindrical shape. It should be noted, however,that the central body 22 may have other shapes or configurations.

In operation, the driver 16 rotates the crankshaft 26 supported withinthe interior volume 24 of the frame 14. In one embodiment, thecrankshaft 26 is coupled to crossheads 30 via connecting rods 28 andcrosshead pins 32. The crossheads 30 further couple to piston rods 90via crosshead nuts. The crossheads 30 are disposed within crossheadguides 34, which generally extend from the central body 22 andfacilitate connection of the cylinders 12 to the compressor 10. In oneembodiment, the compressor 10 includes two crosshead guides 34 thatextend generally perpendicularly from opposite sides of the central bodyor housing 22, although other configurations are also envisaged. As willbe appreciated, the rotational motion of the crankshaft 26 is translatedvia the connecting rods 28 to reciprocal linear motion of the crossheads30 within the crosshead guides 34.

As discussed in further detail below, the crossheads 30 may have alightweight construction. More specifically, certain components of thecrossheads 30 may be formed from a lightweight composite material. Aswill be appreciated, the lightweight construction of the crossheads 30may enable an designer or operator to increase the speed of thecompressor 10, thereby increasing the flow capacity of the compressor10. Furthermore, the increased flow capacity of the compressor 10 withcrossheads 30 formed from a composite material may be realized withoutincreasing the size of the cylinders 12 of the compressor 10. Asdiscussed below, the pins 32 of the crossheads 30 may also be made froma light composite material.

Furthermore, certain embodiments of the crossheads 30 and the pins 32may include a crosshead lubrication system 220. For example, thecrossheads 30 and the pins 32 may have features which enable thecrossheads 30 and pins 32 to function as the crosshead lubricationsystem 220. More specifically, the crosshead lubrication system 220 isconfigured to route oil or other lubricant to bearing surfaces betweenthe crossheads 30, connecting rods 28, and crosshead guides 34,crosshead shoes, and so forth. In this manner, friction, abrasion, andwear may be further reduced within the compressor 10. Additionally,friction, abrasion, and wear may be further reduced within thecompressor 10 due to material characteristics of composite materialsused to form various components of the compressor 10.

As noted above, the cylinders 12 are configured to receive a fluid forcompression. The crossheads 32 are coupled to pistons 36 disposed withinthe cylinders 12, and the reciprocating motion of the crossheads allowscompression of fluid within the cylinders 12 via the pistons 36.Particularly, as a piston 36 is driven forward during a compressionstroke (i.e., outwardly from central body 22 into a cylinder 12) thepiston 36 compresses the fluid within the cylinder into a smallervolume, thereby increasing the pressure of the fluid. A discharge valveof valve assembly 20 may then be opened to allow the pressurized orcompressed fluid to exit the cylinder 12. The piston 36 may then strokebackward, and additional fluid may enter the cylinder 12 through aninlet valve of the valve assembly 20 for compression in the same mannerdescribed above.

FIG. 3 is a cross-sectional side view of an exemplary piston 36, whichmay also be formed from a lightweight composite material or otherlightweight material. In the illustrated embodiment, the piston 36 has agenerally cylindrical shape, with a diameter 38 and a height 40 (e.g.,axial length). Furthermore, the piston 36 has a single piece design. Inother words, the piston 36 is formed from a single composite body 42constructed from a lightweight composite material or other lightweightmaterial. As mentioned above, the composite material may include amatrix material and a reinforcing material. For example, the lightweightcomposite material may be a carbon composite, a fiberglass composite, orother lightweight composite material. Additionally, other lightweightmaterials may be used, such as a plastic, a ceramic, a polyimide, apolyetheretherketone (PEEK), an elastomer such as SA4, or otherlightweight materials. The composite and/or lightweight construction ofthe piston 36 may prevent the piston 36 from undergoing materialcorrosion due to corrosive gases that the piston 36 may contact. Forcertain applications, the lightweight composite material or otherlightweight material may be configured to withstand a greater pressurethan conventional compressor design materials. For example, lightweightcomposite materials may be configured to withstand pressures greaterthan a minimum radial pressure of approximately 100 to 500, 150 to 450,200 to 400, or 300 to 350 MPa. Additionally, the piston 36 may beconfigured for minimal diametrical expansion at a maximum operatingtemperature. In other words, the piston 36 may be constructed from alightweight composite material or other lightweight material that maylimit the expansion of the diameter 38 of the piston at a specifiedtemperature. For example, the lightweight composite material or otherlightweight material may be selected such that the piston 36 undergoesdiametrical expansion of less than approximately 0.001 to 0.003, 0.0015to 0.0025, or 0.0018 to 0.0022 mm at a temperature of approximately 150to 200, 160 to 190, or 170 to 180 degrees C.

Furthermore, a variety of processes may be used to form the singlecomposite body 42 of the piston 36. In certain embodiments, the singlecomposite body 42 may be compressed, molded, or machined. As shown, thesingle composite body 42 of the piston 36 includes a bore 44. As withthe single composite body 42, the bore 44 may be formed using a varietyof processes. For example, in embodiments where the single compositebody 42 is molded, the mold used to form the single composite body 42may be configured to form the bore 44 during the molding process.Alternatively, in embodiments where the single composite body 42 ismachined, the bore 44 may be formed by a machining process such asdrilling. The bore 44 is configured to receive a piston connecting rodto couple the piston 36 to the crankshaft.

The piston 36 also includes a piston ring carrier 46 configured toreceive one or more piston rings. As will be appreciated, pistons ringsdisposed within the piston ring carrier 46 serve to create a gas-tightconnection when the piston 36 is disposed within a piston cylinder. Thepiston ring carrier 46 may be formed from a metal, such as steel. In theillustrated embodiment, the piston ring carrier 46 includes two annulargrooves 48, where each groove 48 is configured to receive a singlepiston ring. In other embodiments the piston ring carrier 46 may include1, 3, 4, 5, or more grooves 48. The single composite body 42 and thepiston ring carrier 48 are integrally formed. For example, for a piston36 formed by a molding process, the piston ring carrier 48 may be placedin a mold used to form the piston 36. Thereafter, the lightweightcomposite material or other lightweight material is poured into themold, and the lightweight composite material or other lightweightmaterial molds with the piston ring carrier 48 to create the integrallyformed piston 36.

FIG. 4 is a partial cross-sectional view, taken within line 4-4 of FIG.3, illustrating an embodiment of a composite material 50 having areinforcing material 52 distributed within a matrix material 54. Asshown, the matrix material 54 is a base material that holds thereinforcing material 52. In other words, the matrix material 54surrounds and supports the reinforcing material 52. For example, thematrix material may be a plastic, polymer, polyester, epoxy, polyimide,polyetheretherketone (PEEK), polypropylene, or other matrix material.The reinforcing material 52 is distributed throughout the matrixmaterial 54 and may serve to enhance the physical and/or mechanicalproperties of the composite material 50. For example, the reinforcingmaterial may be fibers or other particles, such as carbon, glass,ceramics, or other reinforcing material. As will be appreciated, theratio of matrix material 54 to reinforcing material 52 may vary fordifferent composite materials 50. For example, the ratio of matrixmaterial 54 to reinforcing material 52 may be approximately 10:1 to1:10, 5:1 to 1:5, 3:1 to 1:3, 2:1 to 1:2, or 1:1.

FIG. 5 is an exploded side view of a light composite piston assembly 70,illustrating a piston 36 having a multi-part configuration and a pistonrod clamping system 68. Specifically, in the illustrated embodiment, thepiston 36 includes two body portions: a first body portion 72 and asecond body portion 74, each formed from a lightweight compositematerial or other lightweight material and coupled to one another by thepiston rod clamping system 68. As mentioned above, the lightweightcomposite material or other lightweight material may be a carboncomposite, a plastic, a ceramic, a fiberglass composite, a polyimide, apolyetheretherketone (PEEK), an elastomer such as SA4, or otherlightweight composite material, or any combination of these materials.As with the single composite body 42, the first and second body portions72 and 74 may be formed using a variety of manufacturing processes. Forexample, the first and second body portions 72 and 74 may be formedusing a molding process or a machining process. Furthermore, in theillustrated embodiment, the first and second body portions 72 and 74 aresubstantially identical. As a result, the manufacturing of the piston 36may be simplified and streamlined. For example, in embodiments where thefirst and second body portions 72 and 74 are formed using a moldingprocess, a single mold may be used to form each of the first and secondbody portions 72 and 74. In other embodiments of the multi-part piston36, the first and second body portions 72 and 74 may not be identical.In other words, the first and second body portions 72 may have uniquelydifferent configurations.

As shown, each of the first and second body portions 72 and 74 include abase portion 76, an outer lip 78 and an inner hub 80. The outer lip 78and the inner hub 80 extend axially from the base portion 76 toward acentral radial axis 82 of the piston 36. In certain embodiments, theouter lip 78 and the inner hub 80 may each have an annularconfiguration. Between the outer lip 78 and the inner hub 80 is anannular cavity 84. As will be appreciated, the annular cavity 84 of eachof the first and second body portions 72 and 74 provides a lighterweight design of the piston 36. In embodiments where the first andsecond body portions 72 and 74 are formed using a molding process, themold used to form the first and second body portions 72 and 74 may beconfigured to form the annular cavity 84. Alternatively, the annularcavity 84 may be formed by a machining process such as milling orturning.

Each of the first and second body portions 72 and 74 further includesribs 86 extending between the base portion 76 and the inner hub 80. Forexample, the ribs 86 may have a linear (e.g., straight) configuration, aspiral configuration, or a combination thereof. That is, each of theribs 86 may be straight, each of the ribs 86 may be spiraled, or someribs 86 may be straight and some ribs 86 may be spiraled. The ribs 86provide additional structural support for the first and second bodyportions 72 and 74 and the piston 36 as a whole. As with the annularcavity 84, the ribs 86 may be formed with a mold or with a machiningprocess. Each of the first and second body portions 72 and 74 mayinclude 1 to 10, 2 to 8, or 3 to 4 ribs 86.

As mentioned above, the light composite piston assembly 70 includes thepiston rod clamping system 68 (e.g., piston rod 90, piston rod nut 94,etc. discussed below) that clamps or holds the components of the piston36 together. The piston rod clamping system 68 enables the use andassembly of the piston 36 having a multi-part configuration. Forexample, the piston rod clamping mechanism 68 enables the assembly ofthe first and second body portions 72 and 74, where the first and secondbody portions 72 and 74 form the hollow piston 36.

The inner hub 80 of each of the first and second body portions 72 and 74includes an aperture 88 configured to receive the piston rod 90.Specifically, the aperture 88 extends through inner hub 80 and the baseportion 76 of each of the first and second body portions 72 and 74.Furthermore, the aperture 88 includes a recess 92 formed in the baseportion 76 of each of the first and second body portions 72 and 74. Theapertures 88 and recesses 92 may be formed in the respective first andsecond body portions 72 and 74 using a machining process such asdrilling or using a molding process. The recess 92 formed in the firstbody portion 72 is configured to receive a piston rod nut 94.Specifically, when the piston assembly 70 is assembled, the piston rodnut 94 is received by the recess 92 of the first body portion 72 and iscoupled to the piston rod 90, thereby partially securing the piston rod90 to the piston 36. In some embodiments, the piston rod nut 94 and therecess 92 formed in the first body portion 72 may have the same orsimilar geometry. For example, the piston rod nut 94 and/or the recess92 of the first body portion 72 may have a triangular, rectangular,hexagonal, octagonal, or polygonal shape. Specialized assembly tools maybe used to engage with the piston rod nut 94 for tightening or looseningthe piston rod nut 94. When the piston rod nut 94 is coupled to thepiston rod 90 and disposed within the recess 92 of the first bodyportion 72, rotation of the piston rod nut 94 may be blocked. Blockingrotation of the piston rod nut 94 may enable the piston rod 90 and thepiston rod nut 94 to remain coupled together during operation of thecompressor 10.

The recess 92 of the second body portion 74 is configured to receive apiston rod washer 96 (e.g., piston rod cup). When the piston rodassembly 70 is assembled, the piston rod washer 96 is disposed about thepiston rod 90 and is disposed within the recess 92 of the second bodyportion 74, thereby limiting radial movement of the piston rod 90 withrespect to the piston 36. As discussed in detail below, when the pistonrod 90 and the piston rod nut 94 are coupled to one another, the pistonrod 90 and the piston rod nut 94 may axially compress the components ofthe piston 36 together to form the piston 36.

In the illustrated embodiment, piston ring carrier 46 is disposedbetween the first and second body portions 72 and 74. When the pistonassembly 70 is assembled, the piston ring carrier 46 abuts and isdisposed between the outer lips 78 of the first and second body portions72 and 74. Additionally, when the piston assembly 70 is assembled, theinner hubs 80 of the first and second body portions 72 and 74 abut oneanother. Specifically, the apertures 88 and the recesses 92 of therespective first and second body portions 72 and 74 will be operativelyconnected for receiving the piston rod 90 along a central axis 98 of thepiston 36.

FIG. 6 is a cross-sectional side view of the piston assembly 70 of FIG.4, illustrating the piston assembly 70 assembled with the piston rodclamping system 68. The illustrated embodiment includes similar elementsand element numbers as the embodiment shown in FIG. 5. As mentionedabove, when the piston assembly 70 is assembled, the piston ring carrier46 is axially captured between the first and second body portions 72 and74. Specifically, the piston ring carrier 46 abuts and is axiallycaptured between the outer lips 78 of each of the first and second bodyportions 72 and 74. In the illustrated embodiment, pistons rings 120 aredisposed within the grooves 48 of the piston ring carrier 46. Asdiscussed above, the piston rings 120 serve to create a gas-tight sealbetween the piston 36 and a piston cylinder in which the piston 36operates. The piston ring carrier 46 and the first and second bodyportions 72 and 74 are coupled together to form the piston 36. Asmentioned above, the inner hubs 80 of each of the first and second bodyportions 72 and 74 abut one another. Additionally, the annular cavities84 of each of the first and second body portions 72 and 74 are joined toform hollow portions 122 of the piston 36. As will be appreciated, inaddition to the lightweight material construction, the hollow portions122 of the piston 36 help to enable a light weight configuration of thepiston 36. The light weight configuration of the piston 36 allows thepiston 36 to be operated at higher speeds than pistons formed usingconventional designs. As a result, the piston cylinder containing thepiston 36 may realize a larger flow capacity without increasing the sizeof the piston cylinder. Additionally, the light weight design of thepiston 36 reduces the inertial load of the piston, which may increasethe longevity of the piston 36.

As shown, the piston rod 90 is coupled to the piston assembly 70 by thepiston rod clamping system 68, which includes the piston rod 90, thepiston rod nut 94, and the piston rod washer 96. In certain embodiments,the piston rod 90 has a diameter 124 which may be approximately 10 to500, 20 to 400, 30 to 300, 40 to 200, or 50 to 100 mm. A first end 126of the piston rod 90 is coupled to the piston assembly 70. Specifically,the first end 126 is received by the apertures 88 of the first andsecond body portions 72 and 74 of the piston 36. As mentioned above, thepiston rod nut 94 is disposed within the recess 92 of the first bodyportion 72, and is coupled to a portion 128 of the first end 126 of thepiston rod 70. For example, the portion 128 of the piston rod 90 and thepiston rod nut 94 may each be threaded and configured to engage with oneanother. Specifically, when the piston rod nut 94 (e.g., internallythreaded nut) is disposed within the recess 92 of the first body portion72, the piston rod nut 94 is held stationary. In other words, the pistonrod nut 94 may have a configuration, such as a polygonal configuration,whereby the piston rod nut 94 may not rotate about the central axis 98of the piston 36 when the piston rod nut 94 is disposed within therecess 92 of the first body portion 72. Subsequently, the first end 128of the piston rod 90 (e.g., externally threaded rod) may be placedthrough the apertures 88 of the first and second body portions 72 and74, and the piston rod 90 may be rotated about the central axis 98. Inthis manner, the threads of the portion 128 of the piston rod 90 and thethreads of the piston rod nut 94 may engage, thereby coupling the pistonrod 90 to the piston rod nut 94.

Similarly, the piston rod washer (e.g., piston rod cup) 96 is disposedabout a portion 130 of the first end 126 of the piston rod 70 and withinthe recess 92 of the second body portion 74 of the piston 36. The pistonrod washer 96 may be formed from steel, aluminum, or a soft, lightmaterial, and may protect the piston 36 (e.g., the second body portion94) from the piston rod 90. As the portion 128 of the piston rod 90 iscoupled to the piston rod nut 94, e.g., by rotating the piston rod 90about the central axis 98, the piston rod 90 is translated in adirection 132. As a result, a flange (e.g., shoulder) 134 of the portion130 of the piston rod 90 axially abuts the piston rod washer (e.g.,piston cup) 96, which is disposed in the recess 92 of the second bodyportion 74. Additionally, a washer 136 (e.g., a steel washer) disposedbetween the piston rod nut 94 and the first body portion 72 helpsdistribute a load from the piston rod nut 94 to the piston 36. Thepiston rod 90 couples the piston rod nut 94, the piston ring 46, thefirst and second body portions 72 and 74, and the piston rod washer 96in compression to form the piston 36. As the first and second bodyportions 72 and 74 are formed from the composite material 50, the firstand second body portions 72 and 74 may have an increased capability towithstand compressive forces. As discussed in detail below with respectto FIG. 13, the piston rod 90 may have a variety of compositions toenable coupling to the piston 36. For example, certain portions of thepiston rod 90 may have various coatings or surface treatments (e.g.,hard coatings, wear resistant coatings, etc.) to enable the threadedengagement between the piston rod 90 and the piston rod nut 94.

FIG. 7 is a schematic of an exemplary piston cylinder system 150including a light composite piston 36. As discussed above, the lightcomposite piston 36 may be used in a variety of applications, such ascompressors, pumps, and engines. For example, the piston cylinder system150 of FIG. 7 may be used in a combustion engine. The illustratedembodiment of the piston cylinder system 150 includes a fuel injectionsystem 152 coupled to a combustion chamber 154. The fuel injectionsystem 152 includes a controller 156 coupled to a fuel ignition 158, afuel intake or supply 160, and an air intake or supply 162. Thecontroller is configured to control the quantity and timing of fuelinjection and fuel ignition via the fuel intake 160 and the fuelignition 158 in conjunction with the quantity and timing of air supplyinto the combustion chamber 154.

As illustrated, the combustion chamber 154 includes a piston 36 disposedin a cylinder 164. The piston 36 may be an embodiment of the lightcomposite piston 36 described above. For example, the piston 36 maycomprise a single composite body 42 formed from a lightweight compositematerial or other lightweight material. Alternatively, the piston 36 maybe formed form first and second body portions 72 and 74 formed from alightweight composite material or other lightweight material. Otherembodiments of the piston 36 may include three or more body portionsformed from a lightweight composite material or other lightweightmaterial. As the piston 36 moves upward within the cylinder 164, thepiston 36 compresses a combustion volume 166 having the air andeventually fuel from the intakes 162 and 160. For example, the fuelintake 160 may inject the fuel at one or more times during the upwardstroke of the piston 36 as the piston approaches a top dead centerposition. At this point, the fuel air mixture is at an elevated pressureand an elevated temperature due to the compression by the piston 22. Atan appropriate timing, the fuel ignition ignites the fuel-air mixture togenerate hot pressurized combustion gases, which drive the piston 36away from the top dead center position.

FIG. 8 is a cross-sectional side view of an embodiment of the crosshead30, which may be formed from a light composite material or otherlightweight material. As mentioned above, the crosshead 30 is configuredto couple the connecting rod 28 to the piston rod 33, therebytransferring energy from the crankshaft, to the connecting rod 28, tothe crosshead 30, to the piston rod 90 and to the piston 36. In theillustrated embodiment, the crosshead 30 has a crosshead body 178 havinga single-piece configuration.

In the illustrated embodiment, the crosshead 30 has a first aperture 180configured to receive the piston rod 90. For example, the piston rod 90may be coupled to the crosshead 30 within the first aperture 180 usingbolts, nuts, pins, or other clamping means. Additionally, the crosshead30 has a second aperture 182, which may be used to couple the crosshead30 to the connecting rod 28. Specifically, the second aperture 182 ofthe crosshead 30 may be aligned with an aperture or opening in theconnecting rod 28, and the pin 32 may be disposed within the aperture182 of the crosshead 30 and the aperture in the connecting rod 28,thereby coupling the crosshead 30 to the connecting 28. In this manner,the crosshead 30 and the connecting rod 28 may pivot relative to oneanother, while transferring energy from the connecting rod 28 to thepiston rod 90.

As mentioned above, the crosshead 30 may be formed form a lightweightcomposite material or other lightweight material. For example, asmentioned above, the crosshead 30 has a single-piece configuration, andtherefore may be formed from a single lightweight composite material orother lightweight material. In other embodiments, the crosshead 30 mayhave a multi-piece design and may be formed using multiple lightweightand/or lightweight composite materials. The crosshead 30 may be formedfrom lightweight materials such as a ceramic, a matrix-reinforcedmaterial, carbon fibrous materials, a polyimide, a polyetheretherketone(PEEK), an elastomer, or other composite. Additionally, the lightweightcrosshead 30 may be formed from using a molding process, dyeing process,or other machining process. As will be appreciated, the lightweightconstruction of the crosshead 30 may improve the performance of thecompressor 10 by enabling the operation of the compressor 10 at fasterspeeds. Additionally, the longevity and useful life of the crosshead 30may be improved due to the reduced inertial load of the crosshead 30and/or improved wear and/or corrosion resistance of lightweightmaterials, such as ceramics, that may be used to make the crosshead 30.

FIG. 9 is a cross-sectional side view of an embodiment of the crossheadpin 32, which may be formed from a light composite material or otherlightweight material. As shown, the crosshead pin 32 has a cylindricalshape and is configured to be disposed within the second aperture 182 ofthe crosshead 30. In certain embodiments, the crosshead pin 32 may beformed from a lightweight material, such as a ceramic, a polyimide, apolyetheretherketone (PEEK), an elastomer, a carbon-fibrous composite,matrix-reinforced material, or other composite. The crosshead pin 32 maybe formed using a machining process, such as a molding process or dyeingprocess. Additionally, the crosshead pin 32 includes two caps 200disposed on either end of the crosshead pin 32, thereby enclosing acavity 202 formed by the cylindrical shape of the crosshead pin 32. Asshown, the caps include indentions 204 (e.g., annular indentions) whichengage with recesses 206 formed in an inner surface 208 of the crossheadpin 32. In this manner, the caps 200 may be retained within the cavity202 of the crosshead pin 32. In certain embodiments, the caps 200 may beformed from a metal, such as steel or aluminum. As will be appreciated,the lightweight construction of the crosshead pin 32 may improve theperformance of the compressor 10 by enabling the operation of thecompressor 10 at faster speeds.

FIG. 10 is a cross-sectional side view of an embodiment of the crossheadpin 32. More specifically, the illustrated crosshead pin 32 isconfigured for use with the crosshead lubrication system 220. Thecrosshead pin 32 shown in FIG. 10 includes similar elements and elementnumbers as the embodiment of the crosshead pin 32 shown in FIG. 9.

Additionally, the present embodiment of the crosshead pin 32 includesports 222 configured to flow a coolant and/or a lubricant, such as oil,represented by reference numeral 224. For example, the crosshead pin 32includes entry ports 226, which may receive the lubricant 224 from theconnecting rod 28 of the compressor 10. More specifically, the lubricant224 may reach the entry ports 226 from a surface, port, passage, orother portion of the connecting rod 28. As shown, the entry ports 226extend from an outer surface 228 of the crosshead pin 32 to the innersurface 208 of the crosshead pin 32. As a result, the lubricant 224flows into the cavity of the crosshead pin 32. While the illustratedembodiment of the crosshead pin 32 includes two entry ports 226 forreceiving the lubricant 224 from the connecting rod 28, otherembodiments may include any suitable number of entry ports 226 extendingfrom the outer surface 228 to the inner surface 208 of the crosshead pin32.

Moreover, the crosshead pin 32 also includes two exit ports 230,although other embodiments of the crosshead pin 32 may include othersuitable numbers of exit ports 230. From within the cavity 202 of thecrosshead pin 32, the lubricant 224 flows through the exit ports 230 tothe outer surface 228 of the crosshead pin 32. As mentioned above, whenthe crosshead pin 32 is disposed within the aperture 182 of thecrosshead 30 to couple the connecting rod 28 to the crosshead 30, thecrosshead 30 and the connecting rod 28 may pivot relative to oneanother. As a result, the crosshead pin 32 may move or rotate relativeto the crosshead 30, thereby creating a bearing surface between theouter surface 228 of the crosshead pin 32 and an inner surface (innersurface 256 of FIG. 11 below) of the crosshead 30. As will beappreciated, when the lubricant 224 exits the cavity 202 of thecrosshead pin 32 through the exit ports 230, the lubricant 224 may flowalong the outer surface 228 of the crosshead pin 32 between thecrosshead pin 32 and the crosshead 30. In this manner, the lubricant 224may reduce friction, abrasion, and/or wear between the crosshead pin 32and the crosshead 30, as the crosshead pin 32 and the crosshead 30 moverelative to one another. Furthermore, as discussed in detail below withreference to FIG. 11, when the lubricant 224 exits the cavity 202 of thecrosshead pin 32, the lubricant 224 may flow from the exit ports 230into lubricant ports (lubricant ports 254 of FIG. 11) of the crosshead30, from which the lubricant 224 may flow to other portions of thecrosshead 30.

FIG. 11 is a perspective view an embodiment of the crosshead 30. Morespecifically, the crosshead 30 is configured for use with the crossheadlubrication system 220. That is, the crosshead 30 may be a component ofthe crosshead lubrication system 220. As mentioned above, the crossheadlubrication system 220 is configured to transmit a flow of lubricant,such as oil, from a connecting rod (e.g., connecting rods 28 shown inFIG. 2) to various surfaces of the crosshead 30.

In the illustrated embodiment, the crosshead 30 includes outer surfaces250 having recesses 252. More particularly, the recesses 252 formed inthe outer surfaces 250 of the crosshead 30 are configured to receive andflow the lubricant 224, in the manner described below. In certainembodiments, the recesses 252 may be formed in the outer surfaces 250 bymachining or molding. As will be appreciated, the outer surfaces 250 ofthe crosshead 30 are configured to abut and translate along thecrosshead guides 34 of the compressor 10 during operation of thecompressor 10. Therefore, as the lubricant 224 flows within the recesses252 formed in the outer surfaces 250, the lubricant 224 may reducefriction, abrasion, and/or wear between the crosshead 30 and thecrosshead guides 34, as the crosshead 30 moves along the crossheadguides 34.

As shown, the recesses 252 are indentions, canals, depressions,cavities, or other similar formations that the lubricant 224 may flowwithin or along. Additionally, the shape, configuration, or design ofthe recesses 252 in the outer surfaces 250 may vary. Furthermore, therecesses 252 are fluidly coupled to one or more ports 254 formed in thecrosshead 30. More specifically, the ports 254 extend from one of theouter surfaces 250 (e.g., one of the recesses 252), and through thecrosshead 30 to the aperture 182 of the crosshead 30. More specifically,the ports 254 extend to the inner surface 256 of the crosshead 30. Asdiscussed in detail above, the crosshead pin 32 may move (e.g., rotate)relative to the crosshead 30, thereby creating a bearing surface betweenthe outer surface 228 of the crosshead pin 32 and the inner surface 256of the crosshead 30. Moreover, as the crosshead pin 32 moves relative tothe crosshead 30, the exit ports 230 of the crosshead pin 32 mayperiodically align with the ports 254 of the crosshead 30. In thismanner, the lubricant 224 exiting the cavity 202 of the crosshead pin 32through the exit ports 230 may pass into the ports 254 formed in thecrosshead 30. Thereafter, the lubricant 224 may travel through the ports254 to the recesses 252 formed in the outer surfaces 250 of thecrosshead 30. As the lubricant 224 flows within the recesses 252, thelubricant 224 may reduce friction, abrasion, and/or wear between thecrosshead 30 and the crosshead guides 34, as the crosshead 30 movesalong the crosshead guides 34.

FIG. 12 is a schematic of the compressor 10 having the crossheadlubrication system 220, illustrating a flow path 300 of the lubricant224. As will be appreciated, the flow path 300 of the lubricant 224 maybe vary for different embodiments of the crosshead lubrication system220. As mentioned above the lubricant 224 flows from the connecting rod28 to the crosshead pin 32. That is, the lubricant 224 enters thecrosshead pin 32 through the entry ports 226 of the crosshead pin 32.Thereafter, the lubricant 224 exits the crosshead pin 32 (e.g., thecavity 202 of the crosshead pin 32) through the exit ports 230 andenters the crosshead 30 through the ports 254 of the crosshead 30. Thelubricant 224 reaches the recesses 252 formed in the crosshead 30 andlubricants the bearing surfaces between the crosshead 30 and thecrosshead guides 34. After lubricating the bearing surfaces, thelubricant 224 may be collected in a reservoir 302 of the crossheadlubrication system 220. The lubricant 224 may then continue along theflow path 300 to be reused for lubrication of the crosshead 30. Forexample, in certain embodiments, a pump 304 may be used to circulate theflow of the lubricant 224 within the crosshead lubrication system 200.Other embodiments of the crosshead lubrication system 220 may includeadditional components (e.g., along the flow path 300), such as sumps,filters, and so forth.

In certain embodiments, the crosshead 30 and the crosshead pin 32 havingthe crosshead lubrication system 220 may be formed from the lightweightmaterials described above (e.g., lightweight composite materials). Forexample, the crosshead 30 and/or the crosshead pin 32 may be formed withthe composite material 50 described above. That is, the compositematerial 50 may have the reinforcing material 52 distributed within thematrix material 54. For example, the matrix material may be a plastic,polymer, polyester, epoxy, polyimide, polypropylene, apolyetheretherketone (PEEK), or other matrix material. Additionally, thereinforcing material may be fibers or other particles, such as carbon,glass, ceramics, or other reinforcing material. Moreover, the crosshead30 and/or the crosshead pin 32 having the crosshead lubrication system220 may be formed from other lightweight materials, such as a carboncomposite, a plastic, a polyetheretherketone (PEEK) material, polyimide,an elastomer such as SA4, a ceramic, a fiberglass composite, or otherlightweight composite material.

FIG. 13 is a schematic of the piston rod 90, illustrating a materialcomposition of the piston rod 90. As discussed in detail above, thepiston rod 90 couples with the piston rod nut 94 to assemble the piston36 by axially compressing and retaining the components of the piston 36(e.g., the first and second body portions 72 and 74 and piston ringcarrier 46) together. Specifically, the piston rod 90 and the piston rodnut 94 engage in a threaded connection with one another. As the portion128 of the piston rod 90 is coupled to the piston rod nut 94, e.g., byrotating the piston rod 90 about the central axis 98, the flange orshoulder 134 of the piston rod 90 axially abuts the piston rod washer(e.g., piston cup) 96, which is disposed in the recess 92 of the secondbody portion 74. Additionally, the piston rod nut 94 axially abuts thewasher 136 within the recess 92 of the first body portion 72. As aresult, the piston rod washer 96 and the washer 136 cooperativelycompress (e.g., in an axial direction) the first and second bodyportions 72 and 74 and the piston ring carrier 46 together to form thepiston 36. To enable the threaded engagement between the piston rod 90and the piston rod nut 94, the portion 128 of the piston rod 90 includesthreads 320 (e.g., male or external threads), which engage withcorresponding threads 322 (e.g., female or internal threads) of thepiston rod nut 94.

As mentioned above, the piston rod 90 may be formed from a variety ofmaterials. For example, the piston rod 90 may be formed from steel. Inother embodiments, the piston rod 90 may be formed from the compositematerial 50. In such an embodiment, the lightweight construction of thepiston rod 90 may further improve the dynamics of the compressor 10 (orother machine), thereby further improving the efficiency of thecompressor 10. In embodiments where the piston rod 90 is formed from acomposite material, the portion 128 of the piston rod 90 may include acoating or surface treatment 324. For example, the threads 320 of thepiston rod 90 may have the coating or surface treatment 324, such assteel, tungsten carbide, or other coating having a hardness and/or wearresistance that is greater (e.g., at least 1.5, 2, 3, 4, 5, 6, 7, 8, 9,10 times greater) than the piston rod 90 and/or piston rod nut 94. Forexample, the coating or surface treatment 324 may be a metallicmaterial, a ceramic material, or other hard material. The coating orsurface treatment 324 may improve the strength and hardness of thethreads 320. As a result, the threaded connection between the piston rod90 and the piston rod nut 94 may be improved. Similarly, the threads 322of the piston rod nut 94 may include a coating or surface treatment 326.The coating or surface treatment 326 of the piston rod nut 94 may be thesame or different than the coating or surface treatment 324 of thepiston rod 90.

The lightweight construction and configurations of the piston 36,crosshead 30, crosshead pin 32, piston rod 90, and associated componentsis beneficial for a number of reasons. As discussed above, thelightweight configuration of the piston 36 enables the piston 36 to movewithin the piston cylinder 164 at faster speeds than a piston 36 nothaving a lightweight configuration. As a result, the power output of thepiston cylinder system 150, e.g., the power transferred to a crankshaft,increases in an engine. Furthermore, the increase in power output due tothe lightweight construction of the piston 36 may be realized withoutincreasing the size of the piston cylinder 164. The lightweight designof the piston 36 further reduces the inertial load of the piston 36,which may increase the longevity or useful life of the piston 36.Additionally, the reduced inertial load of the piston 36 may increasethe useful life of other moving components in the piston cylinder system150, such as bearings, rings, bushings, and so forth.

Moreover, the lightweight configuration of the crosshead 30 enables thecrosshead 30 to move within the compressor 10 or other machine at fasterspeeds than a crosshead 30 not having a lightweight configuration. As aresult, the power output of the compressor 10, e.g., the powertransferred to a crankshaft, increases. Furthermore, the increase inpower output due to the lightweight construction of the crosshead 30 maybe realized without increasing the size of the piston cylinder 164. Thelightweight design of the crosshead 30 further reduces the inertial loadof the crosshead 30, which may increase the longevity or useful life ofthe crosshead 30. Additionally, the reduced inertial load of thecrosshead 30 may increase the useful life of other moving components inthe compressor 10, such as bearings, rings, bushings, and so forth.

Furthermore, the crosshead lubrication system 220 enables the flow anddistribution of lubricant 224 from the connecting rod 28 of thecompressor 10 to the crosshead 30 and the crosshead pin 32. Morespecifically, the lubricant 224 may flow through ports (e.g., ports 226,230, and 254) formed in the crosshead pin 32 and the crosshead 30 andthrough the recesses 252 formed in the outer surfaces 250 of thecrosshead 30. As a result, abrasion, wear, and/or friction may bereduced between the crosshead 30, the crosshead pin 32, and thecrosshead guides 34 as the compressor 10 operates. In other words, asthe crosshead pin 32, the crosshead 30, and the crosshead guides 34rotate, translate, or move relative to one another, abrasion, friction,and/or wear among the components may be reduced. Additionally, thecrosshead 30 and the crosshead pin 32 having the crosshead lubricationsystem 220 may also have one or more of the lightweight configurationsdescribed above.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein.However, it should be understood that the invention is not intended tobe limited to the particular forms disclosed. Rather, the invention isto cover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the followingappended claims.

The invention claimed is:
 1. A system, comprising: a piston rodcomprising a piston collar, wherein the piston collar radially extendsrelative to a longitudinal axis of the piston rod beyond an outermostdiameter of the piston rod; a piston rod nut coupled to the piston rod;and a piston body, comprising: a first body portion comprising a firstinner hub; a second body portion comprising a recess and a second innerhub, wherein the first body portion and the second body portion arephysically separate; and a piston ring carrier, wherein respective outerlips of the first body portion and the second body portion capture thepiston ring carrier, the respective outer lips extend in an axialdirection relative to a central axis of the piston body, axial end facesof the piston ring carrier axially abut respective axial end faces ofthe respective outer lips of the first and second body portions, and thepiston collar and the piston rod nut capture the first and second bodyportions, and wherein when the piston collar and the piston rod nutcapture the first and second body portions the piston collar is disposedwithin the recess and the first inner hub and the second inner hub abuteach other at an axial location relative to the longitudinal axiscentrally located within the piston ring carrier.
 2. The system of claim1, wherein the piston rod is made of a composite material, wherein thecomposite material comprises a reinforcing material distributed in amatrix material.
 3. The system of claim 2, wherein the piston rodcomprises a first threaded portion, the piston rod nut comprises asecond threaded portion, and the first and second threaded portions areengaged with one another.
 4. The system of claim 3, wherein the firstthreaded portion comprises a surface treatment, wherein the surfacetreatment comprises a ceramic material, a metallic material, or othercomposite material.
 5. The system of claim 1, wherein the first andsecond body portions are made of a composite material, wherein thecomposite material comprises a reinforcing material distributed in amatrix material, and wherein the piston ring carrier is made of ametallic material.
 6. The system of claim 1, wherein the first bodyportion is hollow and reinforced with a first plurality of ribs, and thesecond body portion is hollow and reinforced with a second plurality ofribs, and wherein the first body portion, the second body portion, andan inner surface of the piston ring carrier together define a commonhollow portion within the piston body.
 7. A method, comprising:extending a piston rod through a first aperture of a first body portionof a piston and a second aperture of a second body portion of thepiston, wherein the first and second body portions of the piston arephysically separate; coupling a piston rod nut to the piston rod;disposing a piston rod cup within a first recess of the piston, whereinthe piston rod cup comprises a body and an outer lip axially extendingfrom the body, and the body and the outer lip define a second recess;abutting a collar of the piston rod against the piston rod cup so thatan entirety of the collar of the piston rod is disposed within thesecond recess; and capturing the first and second body portions of thepiston axially between the piston rod nut and the collar of the pistonrod, wherein the collar of the piston rod radially extends relative to alongitudinal axis of the piston rod beyond an outermost diameter of thepiston rod, and wherein capturing the piston between the piston rod nutand the collar of the piston rod comprises capturing a piston ringcarrier axially between respective outer lips of the first body portionof the piston and the second body portion of the piston, the respectiveouter lips extend in an axial direction relative to a central axis ofthe piston, and axial end faces of the piston ring carrier axially abutrespective axial end faces of the respective outer lips of the first andsecond body portions.
 8. The method of claim 7, comprising disposing thepiston rod nut within a third recess of the piston.
 9. The method ofclaim 7, wherein coupling the piston rod nut to the piston rod comprisesengaging a first threaded portion of the piston rod with a secondthreaded portion of the piston rod nut.
 10. The method of claim 7,wherein the first and second body portions are made of a compositematerial, wherein the composite material comprises a reinforcingmaterial distributed in a matrix material.
 11. A system, comprising: apiston having a first body portion physically separate from a secondbody portion; a piston ring carrier; a piston clamping system,comprising: a piston rod comprising a piston rod collar, wherein thepiston collar radially extends relative to a longitudinal axis of thepiston rod beyond an outermost diameter of the piston rod, wherein thepiston collar is configured to be disposed within a first recess of apiston; a piston rod cup configured to be disposed between the pistonrod collar and the piston and within the first recess of the piston,wherein the piston rod cup comprises a body and an outer lip axiallyextending from the body, and the body and the outer lip define a secondrecess, and wherein the piston rod collar is configured to be disposedin its entirety within the second recess; and a piston rod nut coupledto the piston rod, wherein the piston clamping system is configured tocapture the piston axially between the piston rod nut and the piston rodcollar, and wherein when the piston clamping system captures the pistonbetween the piston rod nut and the piston rod collar of the piston rodthe piston clamping system is configured to capture the piston ringcarrier axially between respective outer lips of the first body portionof the piston and the second body portion of the piston, the respectiveouter lips extend in an axial direction relative to a central axis ofthe piston, and axial end faces of the piston ring carrier axially abutrespective axial end faces of the respective outer lips of the first andsecond body portions.
 12. The system of claim 11, wherein the piston rodhas a first threaded portion, the piston rod nut has a second threadedportion, and the first and second threaded portions are engaged with oneanother.
 13. The system of claim 12, wherein the first threaded portioncomprises a surface coating, wherein the surface coating is differentfrom the first composite material.
 14. The system of claim 13, whereinthe surface coating is a metallic material, a ceramic material, or othercomposite material.
 15. The system of claim 11, wherein the piston rodis made of a first composite material, and wherein the first compositematerial comprises a first reinforcing material distributed in a firstmatrix material, and wherein the piston is made of a second compositematerial, wherein the second composite material comprises a secondreinforcing material distributed in a second matrix material.